• Share
  • Email
  • Embed
  • Like
  • Save
  • Private Content
02 Objective C
 

02 Objective C

on

  • 3,747 views

 

Statistics

Views

Total Views
3,747
Views on SlideShare
3,744
Embed Views
3

Actions

Likes
4
Downloads
122
Comments
0

1 Embed 3

http://www.slideshare.net 3

Accessibility

Upload Details

Uploaded via as Adobe PDF

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

    02 Objective C 02 Objective C Presentation Transcript

    • CS193P - Lecture 2 iPhone Application Development Objective-C Foundation Framework Thursday, January 7, 2010 1
    • Announcements Thursday, January 7, 2010 2
    • Announcements • Enrollment process is almost done Thursday, January 7, 2010 2
    • Announcements • Enrollment process is almost done Thursday, January 7, 2010 2
    • Announcements • Enrollment process is almost done • Shooting for end of day Friday Thursday, January 7, 2010 2
    • Announcements • Enrollment process is almost done • Shooting for end of day Friday • Please drop the class in Axess if you are not enrolled. Thursday, January 7, 2010 2
    • Office Hours • David Jacobs ■ Mondays 4-6pm: Gates 360 • Paul Salzman ■ Some time. Best to try all possible times until you hit it ■ Some place, probably in Gates. Just come by and yell real loud Thursday, January 7, 2010 3
    • iPhone SDK Thursday, January 7, 2010 4
    • iPhone SDK Thursday, January 7, 2010 4
    • iPhone SDK • Enrolled students will be invited to developer program ■ Login to Program Portal ■ Request a Certificate ■ Download and install the SDK Thursday, January 7, 2010 4
    • iPhone SDK • Enrolled students will be invited to developer program ■ Login to Program Portal ■ Request a Certificate ■ Download and install the SDK Thursday, January 7, 2010 4
    • iPhone SDK • Enrolled students will be invited to developer program ■ Login to Program Portal ■ Request a Certificate ■ Download and install the SDK • Will need your Device UDIDs - details to come Thursday, January 7, 2010 4
    • iPhone SDK • Enrolled students will be invited to developer program ■ Login to Program Portal ■ Request a Certificate ■ Download and install the SDK • Will need your Device UDIDs - details to come Thursday, January 7, 2010 4
    • iPhone SDK • Enrolled students will be invited to developer program ■ Login to Program Portal ■ Request a Certificate ■ Download and install the SDK • Will need your Device UDIDs - details to come • Auditors will need to sign up for Developer Program independently ■ Free for Simulator development ■ $99 for on-device development Thursday, January 7, 2010 4
    • Getting Help • The assignment walks you through it • Key spots to look ■ API & Conceptual Docs in Xcode ■ Class header files ■ Docs, sample code, tech notes on Apple Developer Connection (ADC) site ■ http://developer.apple.com ■ Dev site uses Google search Thursday, January 7, 2010 5
    • Today’s Topics • Questions from Tuesday or Assignments? • Object Oriented Programming Overview • Objective-C Language • Common Foundation Classes Thursday, January 7, 2010 6
    • Object Basics Thursday, January 7, 2010 7
    • OOP Vocabulary • Class: defines the grouping of data and code, the “type” of an object • Instance: a specific allocation of a class • Method: a “function” that an object knows how to perform • Instance Variable (or “ivar”): a specific piece of data belonging to an object Thursday, January 7, 2010 8
    • OOP Vocabulary • Encapsulation ■ keep implementation private and separate from interface • Polymorphism ■ different objects, same interface • Inheritance ■ hierarchical organization, share code, customize or extend behaviors Thursday, January 7, 2010 9
    • Inheritance Superclass NSObject UIControl Subclass UIButton UITextField • Hierarchical relation between classes • Subclass “inherit” behavior and data from superclass • Subclasses can use, augment or replace superclass methods Thursday, January 7, 2010 10
    • Inheritance Memory Superclass NSObject management UIControl Subclass UIButton UITextField • Hierarchical relation between classes • Subclass “inherit” behavior and data from superclass • Subclasses can use, augment or replace superclass methods Thursday, January 7, 2010 10
    • Inheritance Memory Superclass NSObject management Generic UIControl behaviors Subclass UIButton UITextField • Hierarchical relation between classes • Subclass “inherit” behavior and data from superclass • Subclasses can use, augment or replace superclass methods Thursday, January 7, 2010 10
    • Inheritance Memory Superclass NSObject management Generic UIControl behaviors Specific Subclass UIButton UITextField behaviors • Hierarchical relation between classes • Subclass “inherit” behavior and data from superclass • Subclasses can use, augment or replace superclass methods Thursday, January 7, 2010 10
    • More OOP Info? • Drop by office hours to talk about basics of OOP • Tons of books and articles on OOP • Most Java or C++ book have OOP introductions • Objective-C 2.0 Programming Language ■ http://developer.apple.com/documentation/Cocoa/Conceptual/ ObjectiveC Thursday, January 7, 2010 11
    • Objective-C Thursday, January 7, 2010 12
    • Objective-C • Strict superset of C ■ Mix C with ObjC ■ Or even C++ with ObjC (usually referred to as ObjC++) • A very simple language, but some new syntax • Single inheritance, classes inherit from one and only one superclass • Protocols define behavior that cross classes • Dynamic runtime • Loosely typed, if you’d like Thursday, January 7, 2010 13
    • Syntax Additions • Small number of additions • Some new types ■ Anonymous object ■ Class ■ Selectors • Syntax for defining classes • Syntax for message expressions Thursday, January 7, 2010 14
    • Dynamic Runtime • Object creation ■ All objects allocated out of the heap ■ No stack based objects • Message dispatch • Introspection Thursday, January 7, 2010 15
    • OOP with ObjC Thursday, January 7, 2010 16
    • Classes and Instances • In Objective-C, classes and instances are both objects • Class is the blueprint to create instances Thursday, January 7, 2010 17
    • Classes and Instances • In Objective-C, classes and instances are both objects • Class is the blueprint to create instances method Class method method method Data method method method method Data method method method method method method Data method Data method method method Data method method method method Data method method Thursday, January 7, 2010 17
    • Classes and Objects • Classes declare state and behavior • State (data) is maintained using instance variables • Behavior is implemented using methods • Instance variables typically hidden ■ Accessible only using getter/setter methods Thursday, January 7, 2010 18
    • OOP From ObjC Perspective • Everybody has their own spin on OOP ■ Apple is no different • For the spin on OOP from an ObjC perspective: ■ Read the “Object-Oriented Programming with Objective-C” document ■ http://developer.apple.com/iphone/library/documentation/ Cocoa/Conceptual/OOP_ObjC Thursday, January 7, 2010 19
    • Messaging syntax Thursday, January 7, 2010 20
    • Class and Instance Methods • Instances respond to instance methods - (id)init; - (float)height; - (void)walk; • Classes respond to class methods + (id)alloc; + (id)person; + (Person *)sharedPerson; Thursday, January 7, 2010 21
    • Message syntax Thursday, January 7, 2010 22
    • Message syntax [receiver message] Thursday, January 7, 2010 22
    • Message syntax [receiver message] [receiver message:argument] Thursday, January 7, 2010 22
    • Message syntax [receiver message] [receiver message:argument] [receiver message:arg1 andArg:arg2] Thursday, January 7, 2010 22
    • Message examples Person *voter; //assume this exists [voter castBallot]; int theAge = [voter age]; [voter setAge:21]; if ([voter canLegallyVote]) { // do something voter-y } [voter registerForState:@"CA" party:@"Independant"]; NSString *name = [[voter spouse] name]; Thursday, January 7, 2010 23
    • Method definition examples Person *voter; //assume this exists - (void)castBallot; [voter castBallot]; - (int)age; int theAge = [voter age]; - (void)setAge:(int)age; [voter setAge:21]; - (BOOL)canLegallyVote; if ([voter canLegallyVote]) { // do something voter-y } - (void)registerForState:(NSString*)state party:(NSString*)party; [voter registerForState:@"CA" party:@"Independant"]; - (Person*)spouse; - (NSString*)name; NSString *name = [[voter spouse] name]; Thursday, January 7, 2010 24
    • Terminology • Message expression [receiver method: argument] • Message [receiver method: argument] • Selector [receiver method: argument] • Method The code selected by a message Thursday, January 7, 2010 25
    • Dot Syntax • Objective-C 2.0 introduced dot syntax • Convenient shorthand for invoking accessor methods float height = [person height]; float height = person.height; [person setHeight:newHeight]; person.height = newHeight; • Follows the dots... [[person child] setHeight:newHeight]; // exactly the same as person.child.height = newHeight; Thursday, January 7, 2010 26
    • Objective-C Types Thursday, January 7, 2010 27
    • Dynamic and static typing • Dynamically-typed object ! id anObject ■ Just id ■ Not id * (unless you really, really mean it...) • Statically-typed object ! Person *anObject • Objective-C provides compile-time, not runtime, type checking • Objective-C always uses dynamic binding Thursday, January 7, 2010 28
    • The null object pointer • Test for nil explicitly ! if (person == nil) return; • Or implicitly ! if (!person) return; • Can use in assignments and as arguments if expected ! person = nil; ! [button setTarget: nil]; • Sending a message to nil? ! person = nil; ! [person castBallot]; Thursday, January 7, 2010 29
    • BOOL typedef • When ObjC was developed, C had no boolean type (C99 introduced one) • ObjC uses a typedef to define BOOL as a type BOOL flag = NO; • Macros included for initialization and comparison: YES and NO if (flag == YES) if (flag) if (!flag) if (flag != YES) flag = YES; flag = 1; Thursday, January 7, 2010 30
    • Selectors identify methods by name • A selector has type SEL ! SEL action = [button action]; ! [button setAction:@selector(start:)]; • Conceptually similar to function pointer • Selectors include the name and all colons, for example: ! -(void)setName:(NSString *)name age:(int)age; would have a selector: ! SEL sel = @selector(setName:age:); Thursday, January 7, 2010 31
    • Working with selectors • You can determine if an object responds to a given selector ! id obj; ! SEL sel = @selector(start:); ! if ([obj respondsToSelector:sel]) { ! [obj performSelector:sel withObject:self] ! } • This sort of introspection and dynamic messaging underlies many Cocoa design patterns ! -(void)setTarget:(id)target; ! -(void)setAction:(SEL)action; Thursday, January 7, 2010 32
    • Working with Classes Thursday, January 7, 2010 33
    • Class Introspection • You can ask an object about its class ! Class myClass = [myObject class]; ! NSLog(@"My class is %@", [myObject className]); • Testing for general class membership (subclasses included): ! if ([myObject isKindOfClass:[UIControl class]]) { ! // something ! } • Testing for specific class membership (subclasses excluded): ! if ([myObject isMemberOfClass:[NSString class]]) { ! // something string specific ! } Thursday, January 7, 2010 34
    • Working with Objects Thursday, January 7, 2010 35
    • Identity versus Equality • Identity—testing equality of the pointer values if (object1 == object2) { NSLog(@"Same exact object instance"); } • Equality—testing object attributes if ([object1 isEqual: object2]) { NSLog(@"Logically equivalent, but may be different object instances"); } Thursday, January 7, 2010 36
    • -description • NSObject implements -description - (NSString *)description; • Objects represented in format strings using %@ • When an object appears in a format string, it is asked for its description [NSString stringWithFormat: @”The answer is: %@”, myObject]; • You can log an object’s description with: NSLog([anObject description]); • Your custom subclasses can override description to return more specific information Thursday, January 7, 2010 37
    • Foundation Classes Thursday, January 7, 2010 38
    • Foundation Framework • Value and collection classes • User defaults • Archiving • Notifications • Undo manager • Tasks, timers, threads • File system, pipes, I/O, bundles Thursday, January 7, 2010 39
    • NSObject • Root class • Implements many basics ■ Memory management ■ Introspection ■ Object equality Thursday, January 7, 2010 40
    • NSString • General-purpose Unicode string support ■ Unicode is a coding system which represents all of the world’s languages • Consistently used throughout Cocoa Touch instead of “char *” • Without doubt the most commonly used class • Easy to support any language in the world with Cocoa Thursday, January 7, 2010 41
    • String Constants • In C constant strings are ! ! ! “simple” • In ObjC, constant strings are ! @“just as simple” • Constant strings are NSString instances ! NSString *aString = @”Hello World!”; Thursday, January 7, 2010 42
    • Format Strings • Similar to printf, but with %@ added for objects NSString *aString = @”Johnny”; NSString *log = [NSString stringWithFormat: @”It’s ‘%@’”, aString]; log would be set to It’s ‘Johnny’ • Also used for logging NSLog(@”I am a %@, I have %d items”, [array className], [array count]); would log something like: I am a NSArray, I have 5 items Thursday, January 7, 2010 43
    • NSString • Often ask an existing string for a new string with modifications - (NSString *)stringByAppendingString:(NSString *)string; - (NSString *)stringByAppendingFormat:(NSString *)string; - (NSString *)stringByDeletingPathComponent; • Example: NSString *myString = @”Hello”; NSString *fullString; fullString = [myString stringByAppendingString:@” world!”]; fullString would be set to Hello world! Thursday, January 7, 2010 44
    • NSString • Common NSString methods - (BOOL)isEqualToString:(NSString *)string; - (BOOL)hasPrefix:(NSString *)string; - (int)intValue; - (double)doubleValue; • Example: NSString *myString = @”Hello”; NSString *otherString = @”449”; if ([myString hasPrefix:@”He”]) { // will make it here } if ([otherString intValue] > 500) { // won’t make it here } Thursday, January 7, 2010 45
    • NSMutableString • NSMutableString subclasses NSString • Allows a string to be modified • Common NSMutableString methods + (id)string; - (void)appendString:(NSString *)string; - (void)appendFormat:(NSString *)format, ...; NSMutableString *newString = [NSMutableString string]; [newString appendString:@”Hi”]; [newString appendFormat:@”, my favorite number is: %d”, [self favoriteNumber]]; Thursday, January 7, 2010 46
    • Collections • Array - ordered collection of objects • Dictionary - collection of key-value pairs • Set - unordered collection of unique objects • Common enumeration mechanism • Immutable and mutable versions ■ Immutable collections can be shared without side effect ■ Prevents unexpected changes ■ Mutable objects typically carry a performance overhead Thursday, January 7, 2010 47
    • NSArray • Common NSArray methods ! + arrayWithObjects:(id)firstObj, ...; // nil terminated!!! ! - (unsigned)count; ! - (id)objectAtIndex:(unsigned)index; ! - (unsigned)indexOfObject:(id)object; • NSNotFound returned for index if not found NSArray *array = [NSArray arrayWithObjects:@”Red”, @”Blue”, @”Green”, nil]; if ([array indexOfObject:@”Purple”] == NSNotFound) { NSLog (@”No color purple”); } • Be careful of the nil termination!!! Thursday, January 7, 2010 48
    • NSMutableArray • NSMutableArray subclasses NSArray • So, everything in NSArray • Common NSMutableArray Methods + (NSMutableArray *)array; - (void)addObject:(id)object; - (void)removeObject:(id)object; - (void)removeAllObjects; - (void)insertObject:(id)object atIndex:(unsigned)index; NSMutableArray *array = [NSMutableArray array]; [array addObject:@”Red”]; [array addObject:@”Green”]; [array addObject:@”Blue”]; [array removeObjectAtIndex:1]; Thursday, January 7, 2010 49
    • NSDictionary • Common NSDictionary methods + dictionaryWithObjectsAndKeys: (id)firstObject, ...; - (unsigned)count; - (id)objectForKey:(id)key; • nil returned if no object found for given key NSDictionary *colors = [NSDictionary dictionaryWithObjectsAndKeys:@”Red”, @”Color 1”, @”Green”, @”Color 2”, @”Blue”, @”Color 3”, nil]; NSString *firstColor = [colors objectForKey:@”Color 1”]; if ([colors objectForKey:@”Color 8”]) { // won’t make it here } Thursday, January 7, 2010 50
    • NSMutableDictionary • NSMutableDictionary subclasses NSDictionary • Common NSMutableDictionary methods + (NSMutableDictionary *)dictionary; - (void)setObject:(id)object forKey:(id)key; - (void)removeObjectForKey:(id)key; - (void)removeAllObjects; NSMutableDictionary *colors = [NSMutableDictionary dictionary]; [colors setObject:@”Orange” forKey:@”HighlightColor”]; Thursday, January 7, 2010 51
    • NSSet • Unordered collection of objects • Common NSSet methods ! + setWithObjects:(id)firstObj, ...; // nil terminated ! - (unsigned)count; ! - (BOOL)containsObject:(id)object; Thursday, January 7, 2010 52
    • NSMutableSet • NSMutableSet subclasses NSSet • Common NSMutableSet methods ! + (NSMutableSet *)set; ! - (void)addObject:(id)object; ! - (void)removeObject:(id)object; ! - (void)removeAllObjects; ! - (void)intersectSet:(NSSet *)otherSet; ! - (void)minusSet:(NSSet *)otherSet; Thursday, January 7, 2010 53
    • Enumeration • Consistent way of enumerating over objects in collections • Use with NSArray, NSDictionary, NSSet, etc. NSArray *array = ... ; // assume an array of People objects // old school Person *person; int count = [array count]; for (i = 0; i < count; i++) { person = [array objectAtIndex:i]; NSLog([person description]); } // new school for (Person *person in array) { NSLog([person description]); } Thursday, January 7, 2010 54
    • NSNumber • In Objective-C, you typically use standard C number types • NSNumber is used to wrap C number types as objects • Subclass of NSValue • No mutable equivalent! • Common NSNumber methods + (NSNumber *)numberWithInt:(int)value; + (NSNumber *)numberWithDouble:(double)value; - (int)intValue; - (double)doubleValue; Thursday, January 7, 2010 55
    • Other Classes • NSData / NSMutableData ■ Arbitrary sets of bytes • NSDate / NSCalendarDate ■ Times and dates Thursday, January 7, 2010 56
    • Getting some objects • Until we talk about memory management: ■ Use class factory methods ■ NSString’s +stringWithFormat: ■ NSArray’s +array ■ NSDictionary’s +dictionary ■ Or any method that returns an object except alloc/init or copy. Thursday, January 7, 2010 57
    • More ObjC Info? • http://developer.apple.com/documentation/Cocoa/ Conceptual/ObjectiveC • Concepts in Objective C are applicable to any other OOP language Thursday, January 7, 2010 58
    • Questions? Thursday, January 7, 2010 59